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Monoclonal antibodies to the human homologue of the bacterial 65 kD heat shock protein (hsp) were used to investigate the tissue distribution of endogenous hsp 65 in normal versus rheumatoid synovial tissue, in subcutaneous nodules of patients with rheumatoid arthritis (RA) and in several instances of non-rheumatoid inflammation. A strong reactivity of the anti-hsp antibody was found in the cartilage-pannus junction in rheumatoid joints and in rheumatoid nodules, but not in normal joints or in normal or inflamed kidney or liver (irreversible graft rejection, chronic glomerulonephritis or primary biliary cirrhosis). The findings provide a new hypothetical explanation for a role of T cells reactive with the 65 kD hsp in the generation of both articular and extra-articular lesions in chronic rheumatoid arthritis.

The presence of fibronectin (Fn) in rheumatoid pannus was investigated by an immunoelectron microscopic method using horseradish peroxidase-conjugated antibody to stain Fn. Large amounts of Fn were demonstrated in the interstitial collagenous tissue of invasive rheumatoid pannus. Fn was also observed on the surface of both fibroblast-like and macrophage-like pannus cells, suggesting that it was secreted by these cells and that the secreted Fn might facilitate the spreading of the pannus cells over the cartilage matrix. However, decreased amounts of Fn were observed in areas of contact between pannus cells and the cartilage matrix. The reduction in the amount of Fn demonstrable at the cartilage-pannus junction may be a consequence either of proteolysis of Fn by enzymes secreted at the junction, inhibition of Fn synthesis in cells in contact with cartilage matrix, or transfer of Fn from the pannus cell surface to collagen of the cartilage matrix.

A significant increase in the NaBH4 reducible intermolecular cross-links in the 9 week immobilized rabbit periarticular connective tissue was found. Dihydroxylysinonorleucine, hydroxylysinonorleucine, and histidinohydroxymerodesmosine were the major cross-links which increased during the period of immobilization. No change in the hydroxlysine/lysine ratio between the immobilized and control periarticular connective tissue collagen was detected during the 9 weeks of enforced immobilization of the rabbit knee. Since the collagen mass in the immobilized periarticular connective tissue does not change, or at most is reduced 10%, we suggest that there is an increase in collagen cross-links expressed both in per unit weight of collagen and on the basis of collagen mass per knee due to the lack of physical stress and motion.

Periarticular and peritendinous tissue was investigated in cases of rheumatoid arthritis, osteoarthritis and carpal tunnel syndrome for the appearance of amyloid deposits. In rheumatoid arthritis no amyloid was present. In 7.8% of the cases with osteoarthritis and in 8% of the cases with carpal tunnel syndrome amyloid was present. These amyloid desposits were present essentially in old patients and since no further clinical symptoms of systemic amyloidosis were reported, these deposits are regarded as an age related phenomenon without clinical relevance.

We studied the concentrations of aluminum in the articular tissues of 5 hemodialysed patients treated with aluminum compounds. Aluminum crosses the synovial barrier, is found in synovial fluid (SF) and accumulates in the joint structures (synovial membrane and joint cartilage). The concentrations found in synovial tissue were 2.7 to 10 times control values, in SF 2.5 to 8 times the control concentrations and in cartilage 2.6 times the control concentrations. Transmission electron microscopy showed localization of aluminum in the lysosomal structures and wavelength dispersive microprobe analysis showed aluminum in cellular components associated with phosphate. The possible toxicity of aluminum to joints merits further investigations.

Collagen heterogeneity is now well recognised. 11 different types are known, corresponding to 25 polypeptidic chains. In joints, almost all types of collagen are found. Type II collagen is however predominant, due to its fundamental role in cartilage physiology.

The biochemical and morphological characteristics of the anterior and posterior regions of the rat knee meniscus were studied. The anterior meniscal horn was thicker and contained a lower concentration of DNA, hydroxyproline, and uronic acid as compared to the posterior region. The calcium concentration in the anterior region, however, was significantly greater than the calcium concentration in the posterior horn. Presence of a significant concentration of calcium in the normal rat knee meniscus is unique to rats and uncommon in other mammalian species.

Gout may present in such atypical forms as "primary-chronic", "masked", or "asymptomatic gout at all stages affecting almost any joint. These uncharacteristic presentations were found in 22 out of 124 patients observed. The disease of 4 patients is described as casuistics. Important conclusions of practical use for early diagnosis and early treatment are drawn. Every arthropathy in a male where the diagnosis is not certain, must be suspected as being due to gout. The diagnosis can be assured by detecting urate deposits in the tissue. Determinations of the serum uric acid level can only be indicative since they are subject to a variety of influences. In early disease the x-ray appearances may be described as normal; in later disease as "degenerative" in the joints or in the vertebral column. In an acute relapse the colchicine-test is of high specifity, but its interpretation may be difficult in the primary chronic forms. The other clinical manifestations of the gout syndrome are of high value for the selection of patients in whom urate deposits in the tissue must be sought.

Amyloid deposition in the articular structures occurred with high frequency in a strain of mice now being established as an animal model of senescence in this laboratory. The changes were most evident in the knee joint. Peripheral joints were always spared. The lesions appeared after 7 months of age, and the incidence reached 88% (7 of 8) in autopsied mice over 8 months of age. This is the first report of amyloid deposition in the joints of laboratory animals.

The presence of hydroxyapatite has been determined based on ultrastructure, X-ray diffraction, electron diffraction, and chemical analysis, and confirmed by microprobe analysis in multiple deposits surgically excised from four unrelated patients with tumoral calcinosis. The chemical composition of each of the mineralized deposits resembled bone, rather than dermis, in mineral, uronic acid, total lipid, and complexed acidic phospholipid composition. No collagen abnormalities were detected. However, all of these deposits differed from normal bone mineral, being heavily mineralized and containing larger, more perfect hydroxyapatite crystals. Ultrastructurally, the crystals were both extracellular and within mononuclear cells in close proximity to dilated rough endoplasmic reticulum.

Muramic acid is a component of the peptidoglycan moiety of cell walls of all bacteria and blue-green algae and is not found elsewhere in nature. A gas-liquid chromatography-mass spectrometry assay for muramic acid in tissue is described. The application of the method to the detection of muramic acid in tissues of rats with streptococcal cell wall-induced polyarthritis is demonstrated. Because the method has the potential to measure total bacterial biomass in tissue, it should prove to be an important assay in elucidating the etiological role of bacterial debris in chronic inflammatory diseases in humans.

Arthritis induced with type II collagen in DBA/1 mice, was analyzed by immunohistochemical techniques. In the earliest detectable pathologic changes, before any macroscopic signs, an accumulation of Mac1+, macrophage-like cells, and an increased expression of major histocompatibility class II antigens were observed focally in the synovial lining layer. In these foci, CD4+ and interleukin 2 receptor expressing T lymphocytes were regularly detected, but not usually other sets of lymphocytes such as B lymphocytes and CD8+ lymphocytes. In clinically detectable arthritis, there was a prominent infiltration of Mac1+ cells, both polymorphonuclear-like and macrophage-like cells. T cells were relatively few, suggesting that they do not play a primary effector role, but rather that they may regulate or permit the self-perpetuative inflammation.

We have developed sensitive and specific solid-phase radioimmunoassays to quantitate the distribution and persistence of bacterial antigen in rats developing arthritis in response to a single injection of streptococcal cell wall material. Three separate assays were specific for either the A polysaccharide (N-acetyl-D-glucosamine), A-variant polysaccharide (polyrhamnose), or peptidoglycan (D-ala-D-ala) moieties of the streptococcal cell wall. Antigen was detected in all tissues surveyed, although the greatest amount was in the liver and spleen. By using three fractions of cell wall separated by size, we have shown that the development of arthritis correlates with the degree of cell wall deposited and persisting in the joints. Further statistical analyses suggested differences in metabolism by different tissues and differential metabolism of different antigenic epitopes in some cases.

Immunoreactive proteoglycans (iPGs) and sulphated glycosaminoglycans (GAGs) were assayed in synovial fluid obtained from 22 patients with osteoarthritis (OA), 21 with rheumatoid arthritis (RA), 13 with gout, and five with Reiter's syndrome. A strong positive linear correlation was observed between concentrations of sulphated GAGs and iPGs in RA (r = 0.95) and gout (r = 0.94). A linear correlation was also observed in OA (r = 0.65). Patients with gout and Reiter's syndrome had significantly higher concentrations of sulphated GAGs and iPGs than patients with OA or RA. Patients with gout also had significantly higher total quantities of sulphated GAGs and iPGs in the knee joint cavity than patients with OA or RA. In all four diseases similar profiles were observed when comparisons were made between the total quantities and concentrations of sulphated GAGs and iPGs in synovial fluid. These results indicate that the observed differences in concentrations are not simply a function of dilution. The concentrations of sulphated GAGs and iPGs did not correlate closely with the type or number of inflammatory cells in the synovial fluid. Considerable variation was noted in the sulphated GAG/iPG ratios, suggesting that different mechanisms may be contributing to the release of proteoglycans in the diseases studied.